See convention in Webster's New World College Dictionary
noun
Rare a convening or being convened
an assembly, often periodical, of members or delegates, as of a political, social, professional, or religious group
the members or delegates at such an assembly
in the U.S., an official gathering of delegates of one party to select candidates for office, formulate party policies, etc.
an agreement between persons, nations, etc.: a copyright convention; the Geneva Convention
general agreement on the usages and practices of social life: bohemian revolt against convention
a customary practice, rule, method, etc.; usage: the soliloquy was an Elizabethan dramatic convention
Card Games a bid or play understood by partners to have a special meaning when made by either of them
See convention in American Heritage Dictionary 4
(kən-vĕnˈshən)
noun
a. A formal meeting of members, representatives, or delegates, as of a political party, fraternal society, profession, or industry.
b. The body of persons attending such an assembly: called the convention to order.
An agreement between states, sides, or military forces, especially an international agreement dealing with a specific subject, such as the treatment of prisoners of war.
General agreement on or acceptance of certain practices or attitudes: By convention, north is at the top of most maps.
A practice or procedure widely observed in a group, especially to facilitate social interaction; a custom: the convention of shaking hands.
A widely used and accepted device or technique, as in drama, literature, or painting: the theatrical convention of the aside.